Camera Aperture, F Number, and Depth of Field Explained » i Digital Photo About Aperture – Everything you wanted to know but thought it was uncool to ask If you were to devise a system that was intended to be confusing, you’d have a hard time coming up with anything more confusing than photographic aperture. I’ve so often seen people glaze over within five seconds of the start of an explanation, their minds a whole galaxy away – anywhere, so long as it’s not here listening to f/stops, depth of field and so forth. But when you split it up, it’s pretty easy. So, what is aperture? The basic idea is that light reaches your camera’s sensor (or film) through a hole. With pinhole cameras, it’s literally that: a hole in a light-tight box projects an image on the inside. With cameras, we put some glass around the hole to make the image sharper. But essentially, it’s still a hole. History would have been different if photographers talked about ‘hole numbers’ or adjusting the size of their ‘lens hole’ but somehow that did not sound cool – even in the 1870s. So photographic aperture is the hole in the camera lens which lets light in.

Why size matters As you know from general experience, the bigger a hole, the more can go through it. Think about turning on a tap (water faucet): open it a little and the flow is only a trickle, open it up and more water flows through. It’s the same with lens aperture: the larger the aperture, the more light gets through to the sensor. Obviously this affects the exposure of your image. Now, giving the film or sensor the proper exposure is like filling a cup of water: if the water flow is slow (from a small aperture), it takes longer to fill (the exposure time is longer). And obviously, if the flow is faster (we turn the tap on to make the aperture larger), it takes less time to fill the cup (exposure time is shorter). What do the numbers mean? Now, it’s easy to measure exposure time – directly in seconds or fractions of a second. With the aperture, it was realised early on that simply measuring the size of the hole was not enough. That’s because holes of the same size in different lenses of different designs or focal length will look different to the film or sensor.

A good way to see this is to pick up a pair of binoculars or SLR lens if you have one handy). Look down one end, and turn over and look down the other: the hole will look different sizes – but it’s the same hole. What has changed is the effective focal length. This shot shows a 24mm lens: the aperture is much larger on the sensor side than from the subject side. Basically we need a measure that relates the size of the hole to the focal length. At the same time the measure needs to show that as the size of the hole becomes smaller, less light flows through (and vice versa: bigger aperture lets in more light). The answer is the f/number: we divide the focal length by the effective diameter of the hole. Why are they like that? Suppose we have a 50mm focal length lens. If we have a big size hole – a big aperture, it might measure 25mm. So 50 divided by 25 gives us 2: the f/number is 2, which we write as f/2.

If the aperture is smaller, say, 3mm in diameter, 50 divided by 3 gives us about 16: the f/number reads f/16. As the hole is smaller, less light gets through. So f/16 is said to be a small aperture or small f/number. That’s why you could get confused if you read about an aperture of 16 being smaller than 2: that does not make sense and is, in fact, wrong. A photographic aperture is written as ‘f/number’: it means the focal length divided by the aperture diameter. So f/16 is indeed smaller than f/2. (Microscopists talk about numerical aperture, but that’s a different thing.) f/number sequence The basic f/number sequence is 1.4, 2, 2.8, 4, 5.6, 8 – it’s a doubling every other step – then it falters a bit: 11, 16, 22, 32, 45 but is essentially still a doubling every other step.

Each step to a lower f/number represents a doubling in the area of the aperture, which means a doubling in the amount of light passing i.e. a one-stop increase in exposure. Conversely, each step to a higher f/number means a halving in the area of the aperture, which means reducing exposure by one stop. Don’t worry about why this is (or ask a friendly mathematician if you really want to know): just remember that the sequence means that if you change aperture setting from, say, f/4 to f/8, then the exposure time needs to increase by two stops, and vice versa. What are stops? Here’s another source of confusion. The word ‘stops’ is used in two senses. One goes back to the days when lens aperture was changed by dropping in a metal plate with a hole cut in it. You changed aperture by taking out one plate and dropping in another one with a different sized hole. These were called stops (actually Waterhouse stops, after the inventor). From that we get the term ‘stopping down’. Now, these stops were arranged so that each smaller hole halved the exposure (and conversely, each larger hold doubled exposure). From that we get the term ‘f/stops’.

From this you still hear photographers talk about ‘one stop’ meaning a halving or doubling of exposure. Goes all the way back to late nineteenth century! Carting sets of metal plates with holes in them is a bore, not to mention really slow to use and before long the aperture diaphragm was invented. This was a set of leaves which were pivoted on the rim so that they fanned across the gap – the more they overlapped, the smaller the central hole. And that’s what we still use now. Aperture and depth of field So much for aperture and exposure. What complicates the whole subject further is that aperture affects two quite different things independently. Just as shutter setting contributes to exposure but also influences motion blur, aperture setting contributes to exposure but also influences something else altogether. Aperture is one of the factors controlling depth of field. In fact aperture is the single most powerful and easiest way to control depth of field. What you need to know Use a small aperture like f/16 if you want as much as possible of the image to look sharp. Use a large aperture like f/2.8 to make just your main subject sharp against a blurred background i.e. for minimum depth of field.

In between, an aperture like f/5.6 is good for general uses as it produces an average depth of field. It’s real simple. f/16 How to Set Camera Aperture | eHow How to Set Camera Aperture  Email Save When using a camera with manual controls, you have the option to set the aperture. This allows you to determine how much light to allow into your camera, which affects the overall exposure and how deeply focused your picture will be. Setting the aperture on your camera can give your pictures a variety of looks by blurring out the background or keeping it sharp. It also helps determine how bright or dark your pictures will be. Aperture is one of the components of photographic exposure. Things You'll Need Camera Determine if your camera can have the aperture set. SLR (Single Lens Reflex) cameras and some feature heavy compact digital cameras allow you to set the aperture. Look for a command dial on your camera. If it is labeled with an "Av" or "A," it has the ability to set the aperture manually. Some compact digital cameras hide this feature in a menu system. Understand how the aperture numbering system works. Aperture is given a number value.

If the number is small, the aperture ring is open very wide, allowing a lot of light into your camera. If it is a larger number, the aperture ring is not as wide, allowing less light into the camera. An aperture number of f2.8 is a wider opening than an aperture of f8. If all other settings remain constant, a picture taken with the aperture set at f2.8 will be brighter than a picture taken with an aperture of f8. Adjust the aperture on your camera. Use your camera manual to determine where the aperture setting is on your specific model and brand of camera. Toggle through the numbers, remembering that the lower number will allow more light into the camera. If you are shooting in the fully manual ("M") mode, your shutter speed will stay constant as your set your aperture to different values. Take a few pictures with different aperture values to see how the different settings affect your picture. Use the "Av" or "A" setting on your camera to select the aperture you wish to use. Use the "Manual" or "M" mode to set both the aperture and shutter speed on your camera. Setting the aperture on your camera will also effect the depth of focus in your pictures.

When using a telephoto lens, a small aperture number will make your background get blurry, so your foreground subject is more defined. This is commonly used in portraiture. Using a wide angle lens with a large aperture number will make your subject matter be in focus form front to back. This is a great option for photographing scenery and landscapes. Promoted By Zergnet "The Easy Guide To Understanding Aperture (f Stop)" by Peter Hill | Redbubble Introduction Have you ever asked yourself a question similar to one of these? What’s with all the f/2.8 and f/1.4 and f/22 stuff people use in their Descriptions? Are they just being numerically anal or are they telling us something useful? What’s the freakin’ difference between a 50mm f/1.4 lens and a 50mm f/1.8 lens? Why is one way more expensive than the other? What do people mean when they describe a particular lens as being “fast”? Where is it going? What do lenses have to do with aperture and f stop? Isn’t that what a camera does? What does “stopping down” mean?

If I’m meant to “stop down” why are the f numbers higher? Shouldn’t they be lower? What’s “aperture”? Is “aperture” the same thing as f stop? How does changing aperture change my photograph? I shoot in Auto mode. Why do I need to know about aperture? If you have, they are all good questions and they are all answered in this Tutorial. Seriously technically-minded readers should, however, stop right now and go and do something else lest they get irate at my basic, and potentially overly-simplistic, explanations. My aim is merely this: learning about aperture and f stop is like learning to drive a car. Once you “get it” you never forget it. All it takes is an understanding of a few basic principles, so in my book it doesn’t matter how they are expressed. And if you reach an understanding of aperture and how you can control it, it is my firm view you will take your photography to the next level. By the way, aperture and f stop are indeed references to the same thing. Aperture is the mechanism and f stop is the measure of engagement of the mechanism.

Seeing the light Photography is not about selecting buttons and switches on a highly sophisticated piece of electronic and optical equipment. Photography is about light. Without light, there is no photograph. End of story. Light controls what you see in a photograph and how you see it. And because natural light changes constantly, we need to be able to control its intensity as it passes through the lens and into the camera as we take a photograph. That is what aperture is. It’s one mechanism by which we control the amount of light hitting the camera’s sensor (or film). Other mechanisms, and I think there are only 2, are filters and shutter speed. (Filters are advanced stuff (see for example this ), but shutter speed is not, so I discuss also the relationship between speed and aperture in this Tutorial.) Controlling the light is important because shooting with too much light and you have an over-exposed image, and not enough light gives you an under-exposed image. We’ve all taken those, haven’t we!? Of course, your modern DSLR or Point & Shoot or Digital Compact, being a sophisticated and precise piece of equipment, can compensate for light automatically, should you choose to let it.

But here’s the rub: the camera has the artistic intelligence level of a mud brick, so it will make compensation adjustments purely as a numerical function and without regard to composition or depth of field. Case in point: True story. I once met a photographer (not my girlfriend) who shoots weddings as a sort of pro-hobby to help out her brother’s wedding video business. With no prior experience, she was given a brand new (full-frame) Canon 5D DSLR with an EF 24-105mm f/4 lens and told to leave it on Auto and just concentrate on composition. This she duly did, and was generally taking ok shots. But she was also confused. Every time she focused on a bride’s face in a group shot, the whole group came out focused instead of just the bride. She wasn’t very happy with the equipment as a result, and thought her brother had wasted $5000. It took some patience and some explaining about the role of aperture and f stop in taking a photograph because the expectation held by this Y Gen lady was that today’s technology should do all that stuff.

But bottom line was that if she had shot in Manual mode and set the aperture to f/4 or had shot in AV mode with aperture set at f/4 she would have achieved her aim of selective focus. I demonstrate and explain this later in this Tutorial. How does the aperture control light? Ever seen a science fiction movie where the scene is inside some fantastic spacecraft? The actor walks through a circular doorway and hits a button on the doorway wall and these sliding steel blades suddenly come out from all around the inside of the rim of the doorway and curl inwards towards the centre of the doorway until the space is completely closed up? (with that lovely steel-grinding sound effect!) Well, that ain’t science fiction because such a scene replicates the aperture mechanism of a camera lens (without the noise), as can be seen from this cross-section of the aperture mechanism of a Canon EF 50mm f1.8 II lens: Notice the blades in the centre circle? Count ‘em, there are 5. And they are actually called “aperture blades”. They move in sync in and out depending on the aperture being set (either by you or by the camera).

Notice also that the inside edges of the blades are not round and that the space allowing the light to go through the lens is thus not circular but instead pentagonal. So, whilst the Canon EF 50mm f1.8 II lens will produce exceptionally sharp images at the right aperture, the effect of having 5 non-rounded aperture blades is poor quality bokeh for out of focus (OOF) areas of the image, ie points of light in OOF areas will be pentagonal in shape, not circular. But hey, I can buy this lens brand new for $135, so it doesn’t really matter that much. By comparison, you’d want a macro lens to give you better quality OOF results. This comes at a price. For example, the $1200 Canon EF 100mm f2.8L IS Macro Lens has 9 round aperture blades, thus ensuring perfectly round points of light. (Just something to look for when considering that new lens.) Anyway, back to the photo of the aperture mechanism. Any ideas of what the aperture setting (f stop) is? I’d say it’s reasonably wide open.

Compare it with this chart, which shows the relative width of aperture according to f stop number. It is the standard “full-stop” f-number scale: Not to scale As you can see from the above, an f stop of f/1.4 is really wide. It is letting a lot more light into the lens and ultimately onto the sensor than, say, f/8. Thus: The lower the f stop number, the wider, or bigger, the aperture. So, if someone tells you to “stop down”, they are referring to decreasing the size of the aperture, which is achieved by increasing the f stop number. If I could wave a wand and get everyone to remember just one thing from this Tutorial, that principle would be it. Remember it and you have 95% “got it”. Aperture and shutter speed Given a low f stop number means a wider aperture which in turn means more light being allowed through the lens, changing the aperture for a particular evenly-exposed shot means you need to shoot faster to compensate (or increase the ISO ). This is because shooting faster reduces the amount of light going through the lens. This is the relationship between aperture and shutter speed.

And because both are based on logarithms and standardised, there is a direct link to how much compensation is necessary. For example, and ignoring ISO for the moment, if you have an evenly exposed photograph shot hand-held at f/8 and 1/30th of a second, you could instead re-shoot it at a faster speed to get better definition and focus by also changing the aperture to, say, f/5.6. Most modern digital cameras use a one-third f-stop increment scale, ie 1.0, 1.1, 1.2, 1.4, 1.6, 1.8, 2.0, 202, 2.5, 2.8, 3.2, 3.5, 4.0, 4.5, 5.0, 5.6, 6.3, 7.1, 8.0, 9.0, 10.0, 11.0, 13.0, 14.0, 16.0, 18.0, 20.0, and 22.0.

So, changing the aperture from f/8 to f/5.6 equates to 1 full stop, and thus you need to increase the shutter speed by the same increment to maintain the even exposure. The numeric expression of the relationship between aperture and shutter speed has been described elsewhere as “The aperture is proportional to the square root of accepted light, and thus inversely proportional to the square root of required exposure time, such that an aperture of f/2 allows for exposure times one quarter that of f/4.” Whatever. Maximum and minimum apertures All lenses have a maximum and a minimum aperture at which they can be used. These limits are known and clearly communicated by the lens manufacturer because each lens is different and thus the aperture range does affect a buyer’s choice. So, if a lens has a stated aperture range of f/2.8 to f/22 it means the smallest aperture at which the lens can be shot is f/22 (the minimum) and the largest aperture is f/2.8 (the maximum). That’s a fairly typical range, as is f/4 to f/32.

When you see someone describe their lens as, say, the Canon EF 50mm f/1.4, they are telling you the image was shot with a lens with a maximum possible aperture of f/1.4. It doesn’t mean they shot the image at that aperture, but it is a way of specifying which particular lens was used. But what about zoom lenses and this type of description? Canon EF 70-300mm f/4-5.6 Zoom Lens. What that means is that when shooting with this lens at a 70mm focal length, the maximum aperture possible is f/4, whereas at 300mm the maximum possible aperture is f/5.6. This compares with the Canon EF 24-70mm f/2.8L Zoom Lens, which means that the maximum possible aperture is f/2.8 regardless of the focal length. As a general proposition, it is also possible that Auto Focus is more precise the larger the maximum aperture. Canon, for example, certainly make this claim in relation to their EF lenses. What’s a fast lens? It is generally accepted that an aperture of f/2.8 is pretty wide.

Since the wider the aperture, the more light, and the more shutter speed required to compensate, a lens with a maximum aperture of f/2.8 or more is described as “fast”. Such lenses are desirable because: Better “stop-action” is achieved with faster shutter speeds, especially hand-held shots. Lowly or poorly lit shots are made easier to achieve without noise from ramping up the ISO to compensate, and/or without a flash, and/or without a tripod. And those are two reasons why people drool and salivate over such lenses as the Canon EF 24mm f/1.4L II, the Canon EF 50mm f/1.2L and the Canon 85mm f/1.2L II lens. The fact that these particular lenses are way out of our price range is also why people look at alternatives, such as the Canon EF 50mm f/1.4 and, say, the Sigma 50mm f/1.4 – much cheaper yet still fast. There is also the Canon 50mm f/1.0L lens which has attained mythical status because it is no longer sold new.

It can be obtained from between $3000 and $4500 second-hand and was, until recently, the fastest interchangeable SLR lens in the universe. That status is now held by the Leica Noctilux 50mm f/0.95 lens – released in 2008 and a steal at $11,000. But wait, there’s more There’s one other reason why a “fast” lens is desirable. Bokeh. The wider the aperture, the narrower the depth of field. This can be simply demonstrated by the following two photographs. The first was taken at f/32, the second at f/5.6: You get the picture. Varying your aperture can also be a very effective way of shooting portraits. For example, this is an image of my youngest son: It was shot hand-held with a Canon EOS 5D Mark II and a Sigma 50mm f/1.4 EX DG HSM lens, using available light indoors. The aperture I used was f/1.4.

For a portrait like this, such a wide aperture allows so much light in through the lens that perfect focus is only achieved for a very narrow vertical focal plane, in this case Dylan’s nose, ie at the front of his face. Every other feature of his face is blurred because none of it was on the same vertical focal plane as his nose (thank goodness!). In hindsight, I should have tried harder to focus on his eyes, but I had only recently acquired the lens and was basically experimenting. The next shot was taken with the same camera and lens, under similar lighting conditions, but with an aperture of f/1.8. It is a casual shot of Linda, who has been a very good friend of mine for 30 years. She has just retired from 35 years of primary school teaching. Notice how on this occasion, the vertical focal plane is not as narrower at f/1.8 as it was with Dylan at f/1.4. It’s not much of a difference but it is enough of a difference to affect the outcome of a portrait shot.

Now compare those shots with the following portrait, Leila, shot by Tatiana with a Canon 5D and a Canon 85mm f/1.8 Lens at f/2: Notice that Tatiana has been very selective in her use of a slightly wider aperture and the angle of the profile to get Leila’s eye and cheek in focus. All 3 of the above shots were taken in the Manual shooting mode. That is, the aperture was deliberately chosen. Would the camera have chosen the same apertures had we been shooting in Auto? Absolutely not. (See also the discussion below on shooting in Aperture Priority mode.) All 3 were also all shot from roughly the same distance from the subjects, but you can (hopefully) imagine that the farther away the subject, the narrower the aperture needs to be. For example, the next shot was taken by my good friend Crispin with his new camera, the Canon 1D Mark IV, and a Canon EF 70-200mm f/2.8L IS Zoom Lens + 2.0 x converter, at a focal length of 400mm (!).

He used an aperture of f/5.6 but even so, there is a drop-off of focus on Avril’s face. Crispin understands aperture very well. I know this because his photography stands out for his control of DOF through the aperture he selects and given the lens he selects for the shot. For example, he understands the creative effect a wide aperture can have on his DOF: Ducking Across The Yellow Brick Road Canon 5D, Canon EF 85mm f1.2L USM lens at f/1.2 Morning Dew Canon 5D Mark II, Canon EF 180mm f/3.5 Macro Lens at f/3.5 Taj Mahal Bench Canon 5D Mark II, Canon EF 24-105mm f/4 IS Lens at f/9 An interesting thing about that last shot, taken by Crispin at f/9, is the broad DOF. In fact, setting an aperture of smaller than f/9 on the 5D Mark II, ie f/11, f/16 and so on, will not achieve any greater DOF.

This is due to the Diffraction Principle, which applies to DSLRs with a large amount of pixels available to the sensor. In the case of the full frame 5D Mark II, 21.6 megapixels are competing for the narrow light created by such small apertures, so much so that definition is not improved. And this is why I would only shoot at f/11 and down further when using my own 5D Mark II to prolong a long exposure. If that camera has a downside, the application of the Diffraction Principle is it. Aperture Priority I’m a strong advocate of not shooting in Auto mode (where the camera makes all the decisions on settings) unless circumstances dictate quick, responsive, shooting. I shoot almost exclusively in Manual mode (where I make all the decisions), but I also shoot in Aperture Priority mode when using my film SLR, the Canon EOS-3. What is Aperture Priority? Turning your camera’s Mode Dial to AV (which stands for Aperture value) means that you set the aperture you want and the camera compensates by making the decisions on shutter speed. This is a particularly good way of ensuring you achieve the DOF you want from your image.

(Just remember that, as with Shutter Priority mode (TV) and Auto mode, the camera will compensate for even exposure, whereas in some cases you may not be looking for that level of light control. That’s why I shoot in Manual.) Related to this, many of the newer digital cameras now offer DOF preview, which means that once you have composed and focused your shot, you can press a button on the camera with a finger on your left hand, whilst scrolling through the various f stops with a finger on your right hand, and see the changes to DOF through the viewfinder as you scroll through the apertures. Cool. Group f/64 This story would not be complete unless I quickly mention Group f/64. One hundred years ago, Pictorialist photography was the thing. Grainy, soft focus, dark-toned images, created in the darkroom by a variety of manual techniques, was the height of photographic fashion. Much like the opportunities provided by today’s Photoshop with its textures and layers, back then such creativity boomed in the hands of the motivated.

Another explanation I’ve heard of the birth of Pictorialism was that it was pursued to demonstrate the legitimacy of photography as a valid form of art, in part to overcome the overwhelming contemporary perceptions of photography stemming from Kodak enabling the masses to literally point and shoot with the mass-produced Box Brownie. Group f/64 was a conclave of photographers who railed against pictorialism, among the founders being Ansel Adams and Edward Weston. Their aim was to promote the cause of photography as it was shot. And they shot as their eyes saw, with perfect focus throughout the frame – foreground, background, and everywhere in between. Their cameras were large format and f/64 was the smallest aperture possible to give that clarity, especially in landscapes. We digital camera users can do nought but dream about using f/64. Either that or dream about picking up a few long lost Ansel Adams negatives in a garage sale. Now wouldn’t that make your day? Conclusion Well, I’ve looked at the questions at the start of the Tutorial and I think I’ve answered them. I hope the answers are able to facilitate anyone’s understanding.

Cheers Peter Acknowledgments The 2 flower images were taken by Fir0002 and are used with permission granted under the terms of the Wikipedia GNU Free Documentation License . The image of the aperture mechanism of a Canon EF 50mm f1.8 II Lens was taken by Adam Wysocki and is used with permission granted under the terms of the Wikipedia GNU Free Documentation License . The graphic of the relative f stop sizes was created by Chris Buckley and is used with permission granted under the terms of the Wikipedia GNU Free Documentation License . The images taken by Tatiana and Crispin are used with their kind permission. History 13 August 2010 – Tutorial published 20 August 2010 – Additional content on Aperture Priority added Camera Exposure Basics: Shutter Speeds, Aperture, F Stops, and ISO - ​Easy Basic Photography ​Easy Basic Photography Mini Gallery Flower Photography Camera Exposure Basics: Shutter Speeds, Aperture, F Stops, and ISO ​In photography, the term exposure is a reference to how much light, and how long that light is exposed to the cameras' image sensor when the camera shutter release is pressed.

In simple terms, the camera's exposure value settings determine if an image will be too light, too dark, or correctly exposed according to normal standards.​​ Overexposed Image Better or "Correct" Exposure Underexposed Image ​The correct or desired exposure is obtained by using a combination of the camera's Lens Aperture setting, the Shutter Speed , and the ISO setting. Those three functions are commonly known as the "Exposure Triangle". All digital cameras have automatic shooting modes which enable you to just pick up your camera and start taking pictures without having to worry about the settings for a correct exposure. That would include basic compact cameras like the ﻿﻿ Canon Powershot Elph 170 IS. ﻿﻿ Still, it is good know what the camera is doing to obtain the exposure even with a basic compact camera. That is just in case you need to change from the full automatic mode to a scene mode like night landscape or back lit portrait to adjust for various light conditions. However, Digital SLR cameras like the ﻿ Nikon D3300 ﻿, or Mirrorless Compact System cameras like the Sony Alpha a5100 allow you to manually adjust all of the camera's exposure settings.

Some "Bridge" or Advanced type compact cameras also allow you to manually choose specific settings to adjust the exposure. With most basic compact cameras , the exposure settings are automatically set and cannot be manually adjusted. Camera Lens Aperture Diagram What are the functions of the Aperture, Shutter, and ISO rating? As previously mentioned, the camera lens aperture, the camera shutter, and the ISO function work together to produce a correctly exposed image. Lets take a look at each of these functions individually, and then how they work in relation to each other. The Lens Aperture: The camera lens aperture, or more specifically, the size of the lens aperture opening determines the amount of light that reaches the camera's image sensor . The camera lens aperture diagram on the right shows the relative size of the aperture openings at different settings. The various lens aperture settings are called "F Stops". The aperture settings with the lower F Stop numbers allow more light to reach the image sensor than the settings with the higher F Stop numbers. Listed below is an aperture chart. The F Stop numbers in red represent ​a full stop and the numbers in black are 1/3 increments between the full stops.

A full stop in either direction will allow twice as much light, or half as much light to reach the image sensor. ​For example, F4 allows twice as much light to reach the cameras' image sensor than F5.6. On the other hand, F8 allows half as much light to reach the sensor than F5.6. Picture #1, Aperture F10, Shutter Speed 1/400 sec, ISO 64 Picture #2, Aperture F5, Shutter Speed 1/400, ISO 64 Take a look at picture # 1. It was taken with the lens aperture set to F10 and is much darker than picture # 2, which was taken with an F5 aperture setting. That is because the wider aperture opening of F5 allows more light to reach the image sensor than the smaller aperture opening of F10. In this example, the shutter speed and ISO settings are the same in both pictures. ​You can see that even though the only setting that was changed was the lens aperture, the images look totally different. ​Another important feature of the camera lens aperture is its effect on the Depth of Field in an image.

Depth of field is a reference to how much of the image, (subject, foreground, and background) will be in focus. Using a wide aperture such as F2.8 or F3.5 can produce an image similar to picture # 3. Notice how the flower is in focus but the background area is out of focus. That effect is referred to as narrow, or shallow depth of field. Picture #3, Shallow Depth of Field Picture #4, Deep Depth of Field Using a smaller aperture opening like F11 or F16 might produce an image like picture #4 where just about everything is pretty much in focus. That effect is called wide or deep depth of field. However, take note that there are other factors such as the lens focal length,the lens to subject distance, and the type of camera lens being used that will also affect the depth of field in an image. The Camera Shutter: The shutter speed determines the length of time that light will be exposed to the camera's image sensor. Shutter speeds are listed in seconds or fractions of a second. Those times reflect how long the camera shutter will be open during an exposure. Listed below is a chart showing shutter speeds in full steps and in 1/3 step increments.

​The numbers in red represent a full step or stop.A shutter speed of 1/60th of a second keeps the shutter open longer than a shutter speed of 1/125th of a second.Changing the shutter speed by a full or partial step in either direction is the equivalent of changing the lens aperture setting by a full or partial F Stop in the same direction. Lets refer back to picture # 1 in the lens aperture section. It is clearly too dark. The underexposure was corrected by changing the aperture setting from F10 to F5 which allowed more light to reach the image sensor. However, If you wanted to lighten that same picture without changing the aperture setting, you could simply change your shutter speed instead. Changing the shutter speed from 1/400 to 1/100 will allow the light to be absorbed by the image sensor for a longer period of time. That change will yield the same basic result as changing the aperture from F10 to F5. The point here is that changing the shutter speed by any given amount of "steps" or increments will have the same effect as changing the aperture by an equal number of steps.

(as long as the change is in the same direction) The shutter speed also has an effect on the look of an image when there is motion in a scene. If there is fast movement in a scene, you might need to use a fast shutter speed to avoid motion blur. Take a look at the moving car in picture # 5. The car in the picture is blurred because the shutter speed of 1/60 was not fast enough to "freeze" the subject. The car in picture # 6 was shot using the faster shutter speed of 1/250 which was fast enough to "freeze" the movement of the car. Picture #5, Shutter Speed 1/160 Picture #6, Shutter Speed 1/250 Picture #7, Shutter Speed 1 second, Aperture F3.4, ISO 400 On the other hand, there may be times when using a slower shutter speed might be your best or only option. For instance, if you try to take pictures at night using a shutter speed like 1/250,they will almost certainly come out black or severely underexposed. Sometimes that will happen even if you use your widest lens aperture opening.

( ​(Also, for this example, assume that the camera ISO is not at its highest setting. ISO settings are covered next) Picture #7 was taken in a fairly well lit area by night photography standards.The shutter speed was 1 full second with a somewhat wide aperture setting of F 3.4. Can you imagine what the image would look like if it had been taken using a shutter speed of 1/250? (assuming the same lens aperture and ISO settings were used) The ISO Function: The ISO setting determines the image sensors' sensitivity to the available light. Lower ISO number settings will require more light for the image sensor to produce a good image than when the camera is set to a higher ISO number. A camera set to ISO 400 will need less light to produce a correctly exposed image than when it is set to ISO 100. ​The following are a few of the most common ISO settings. (there may be more that show in your camera but we will just use these to keep things simple) It is usually best to use lower number ISO settings when taking pictures. That is because the overall quality of the image will be better.

Higher ISO number settings tend to produce grainy images that have tiny specks called digital camera "noise" (Check the tutorial "What is ISO" for an example) However, there may be times that using a higher ISO setting might be the best way to go. A simple example might be when you are in a poorly lit place and your pictures are coming out too dark. If your camera is set on ISO 100, change it to ISO 200, ISO 400 or whatever setting gives you a lighter picture. (the example refers to situations where the shutter speed and aperture settings are not the primary concern) Remember, the higher number ISO settings require less light to produce a well exposed picture. Here is another example of when you might need to change the ISO setting. Lets say you are at an indoor sporting event with lots of fast movement. Your camera is set to ISO 100. The cameras' exposure metering system suggests a lens aperture setting of F4 and a shutter speed of 1/30 for a correctly exposed picture. (assume that F4 is your maximum aperture width) You know that a shutter speed of 1/30 won't be fast enough to "freeze" the action.

However, a shutter speed of 1/250 should work well. Change your ISO setting from ISO 100 to ISO 800. Next, change your shutter speed from 1/30 to 1/250. You will probably be able to take a properly exposed picture with the action "frozen" instead of blurred. As you have probably noticed, changing the ISO setting by a certain number of steps is the same as changing the shutter speed the same amount of steps. That principle also applies to the ISO in relation to the aperture setting. Aperture Priority, Shutter Priority, and Program modes: The majority of material in this tutorial refers to using your camera in the Manual mode where you can set the lens aperture, shutter speed, and ISO separately. Just remember that you don't always have to set each function individually each time you take a picture. Try using one of your cameras' semi automatic modes. If the shutter speed is most important to you for a particular shot, try using the Shutter Speed Priority mode. When using the Shutter Speed Priority mode, you set the desired shutter speed,and the camera will automatically set the aperture that should produce a correctly exposed image.

On the other hand, if the lens aperture setting is most important to you, try using the Aperture Priority mode. You choose the lens aperture setting you want to use and the camera will set a shutter speed that should produce a correctly exposed picture. Lastly, if you aren't concerned about shutter speeds or aperture settings but want to change your ISO setting, just use your camera's program mode. In the program mode the camera will automatically choose the shutter speed and aperture setting for the best exposure. In the Program Mode you will still be able to change the settings for things like the ISO and White Balance. ​ Understanding Aperture and How to Use It in Photography by Jo Plumridge Updated October 17, 2016 When shooting photos with an advanced camera, you're going to want to understand the answer to the question: What is aperture? By controlling the aperture of the camera's lens, you're going to greatly change the way your photos look. Aperture is the term used to describe the amount of light that passes through a camera lens. DSLR lenses have an iris within them, which will open and close to allow certain amounts of light to reach the camera's sensor. The camera's aperture is measured in f-stops.

Aperture has two functions on a DSLR -- as well as controlling the amount of light passing through the lens, it also controls depth of field. The Range of F-Stops F-stops pass through a huge range, particularly on DSLR lenses. Your minimum and maximum f-stop numbers will depend, however, on the quality of your lens. Image quality can drop when using a small aperture (we'll explain that term later in the article), and manufacturers limit the minimum aperture of some lenses, depending on their build quality and design. Most lenses will at least range from f3.5 to f22, but the f-stop range seen across different lenses can be: f1.2, f1.4, f1.8, f2, f2.8, f3.5, f4, f4.5, f5.6, f6.3, f8, f9, f11, f13, f16, f22, f32, f45 DSLRs have more f-stops than many film cameras. Aperture and Depth of Field Let's start with aperture's simplest function first: Its control of your camera's depth of field.

Depth of field simply means how much of your image is in focus around your subject, meaning a small depth of field will make your main subject sharp, while everything else in the foreground and background will be blurry. A large depth of field will keep all of your image sharp throughout its depth. You use a small depth of field for photographing things such as jewelry, and you use a large depth of field for things like landscapes. There is no hard or fast rule, though, and much of choosing the right depth of field come from your own personal instinct as to what will suit your subject matter. As far as f-stops go, a small depth of field is represented by a small number. For example, f1.4 is a small number and will give you a small depth of field. A large depth of field is represented by a large number. For example, f22 is a large number and will give you a large depth of field. Aperture and Exposure Here's where it can be confusing. When we refer to a "small" aperture, the relevant f-stop will be a bigger number. Therefore, f22 is a small aperture, whereas f1.4 is a large aperture.

It's extremely confusing and illogical for most people as the whole system appears to be back to front! What you need to remember is that, at f1.4, the lenses iris will be wide open and allowing a lot of light through. Therefore, it is a large aperture. Another way to help remember this is to recognize that aperture actually relates to an equation where focal length is divided by aperture diameter. For example, if you have a 50mm lens and the iris is wide open, you might have a hole that measures 25mm in diameter. Therefore, 50mm divided by 25mm equals 2. This translates to a f-stop of f2. If the aperture is smaller (for example 3mm) then dividing 50 by 3 gives us a f-stop of f16. Changing apertures is referred to as "stopping down" (if you are making your aperture smaller), or "opening up" (if you are making your aperture larger). Aperture's Relationship to Shutter Speed and ISO As aperture controls the amount of light coming through the lens onto the camera's sensor, it has an effect on the exposure of an image.

Shutter speed , in turn, also has an effect on exposure, as it is a measurement of the amount of time that the camera's shutter is open. Therefore, as well as deciding on your depth of field via your aperture setting, you need to remember how much light is entering the lens. If you want a small depth of field and have chosen an aperture of f2.8, for example, then your shutter speed will need to be relatively fast so that the shutter is not open for long, which could cause the image to overexpose. A fast shutter speed (such as 1/1000) allows you to freeze action, while a long shutter speed (such as 30 seconds) allows for nighttime photography without artificial light. All exposure settings are determined by the amount of light available. If depth of field is your primary concern -- and it often will be -- then you can adjust the shutter speed accordingly. In conjunction with this, we can also change the ISO of our image to help with lighting conditions. A higher ISO (represented by a higher number) will allow us to shoot in lower lighting conditions without having to alter our shutter speed and aperture settings.

However, it should be noted that a higher ISO setting will cause there to be more grain (known as "noise" in digital photography) and image deterioration can become obvious. For this reason, I only ever alter ISO as a last resort. Continue Reading

Question: If you wanted to let more light into a camera lens, would you choose a lower or a higher aperture number (f-stop)?
Answer: Lower